Temperature-sensitive swelling behavior of polymer gel composed of poly (N,N-dimethylaminoethyl methacrylate) and its copolymers

Polymer gels composed of N,N-dimethylaminoethyl methacrylate (DMAEMA) and acrylamide (AAm) (or ethyl acrylamide (EAAm)) were prepared to observe temperature-sensitive swelling behavior. The temperature dependence of equilibrium swelling of poly (DMAEMA-co-AAm) gel was in accordance with the change of the lower critical solution temperature (LCST) of poly (DMAEMA-co-AAm) aqueous solution as a function of chemical composition. However, poly (DMAEMA-co-EAAm) gel did not show the similar trend to poly (DMAEMA-co-AAm) gel. In the case of poly (DMAEMA-co-AAm), the hydrogen bond, which played an important role in controlling the LCST, was maintained with the formation of the gel network. However, the hydrogen bond in poly (DMAEMA-co-EAAm) was disrupted significantly with the formation of the gel network. This led to the difference in swelling behavior of polymer gels in response to temperature. (C) 1999 Elsevier Science Ltd. All rights reserved.